Sneakyturtle
Songster
How tall is your run? If it doesnt have anything on top of it, then fast growing fruit trees like mulberry trees would be good. If it’s got a top, you can still plant small trees like patio peach. Just make sure you put a welded wire fence around it until it’s established. My chickens free range on 10 acres, but they still demolish pretty much everything they have access to but the trees.